Homework Check!

[Viridian]

No more need to check it for me!

I handed it in on friday 10/12 or 12/10 depending on what country you live in :)

 

Hi peoples ^^

 

This friday I have to hand in a project, and I'm almost finished with it. I only need to insert some mathematical information which won't be of big importance anyway.

 

So here it goes! My question for you guys is, can you understand what I did and would you be able to do it yourself? PS: it seems like a lot of reading but really, there are more images than text (okay not really.... :whistle: ) Please help me out since I need it to be understandable for someone who doesn't know a single thing about algae.

 

Click here to download. (.docx)

Click here to download. (.doc)

 

Note: These things are fixed in the actual paper

 

- Index page updated

- Grammar issue: algae grow exponentially

[antiaircraft]

It looks good. :yes: I had no trouble understanding the experiment. The only ambiguous point I found was your results table - it's not very clear what the units are for the rows "Algae Jar 1" and "Algae Jar 2", or why there are two comma-separated sets of results. You might also want to quickly grammar check everything before submitting it.

 

Apart from that, it's a pretty awesome report. :D

 

Incidentally, it appears we have very similar graphical calculators. :P

[Viridian]

It looks good. :yes: I had no trouble understanding the experiment. The only ambiguous point I found was your results table - it's not very clear what the units are for the rows "Algae Jar 1" and "Algae Jar 2", or why there are two comma-separated sets of results. You might also want to quickly grammar check everything before submitting it.

 

Apart from that, it's a pretty awesome report. :D

 

Incidentally, it appears we have very similar graphical calculators. :P

Ah, we europeans work with , instead of . to seperate decimals. ;)

[Unstream]

I'd love to check it out, but the file is in a .docx format, and I can't read that xD

 

Mind saving it as a .doc for me really quickly?

[antiaircraft]

Ah, we europeans work with , instead of . to seperate decimals. ;)

Oh oh OH! Blast! I forgot! xD But still, what are the units?

 

Will, I think Iris had to leave for a while - I can send you a converted copy if you like. :yes:

 

Edit: I stand corrected. :P

[Viridian]

Oh right, totally forgot that might be an issue. Here you go :)

 

Edit: Do we always post at the same time Theo? units are... algae.. 1 cell, you know :P

[Viridian]

Sorry mods for the double post, but I'd really like someone else to have a look at it before I hand it in tomorrow. :)

[arliona]

Whee, biology student here! (I might know a little to much about algae...).

 

Page 3: you wrote "micro algae who", this should be which.

Page 5: "The prepared liquid exists of water and nutrition". I think you have the wrong verb here, I don't understand the sentence.

"a program called imagefocus": Capital I

"After the counting process there will be determined if there can be spoken about exponential growth.". The sentence doesn't work. Try something like: After the counting process (it will be determined / we will determine) if the growth is (indeed/truly/...) exponential.

 

I agree that you need to indicate the units in you result tables. For example, is it just a number of cells, or a concentration in cells/liter? That should be obvious just from reading the table. Adding the note "(cells)" won't look ridiculous, I promise!

 

Also, this could be due to different habits/expectations in your country, but I would expect to see a conclusion/interpretation part after the results. As a clueless reader, I shouldn't have to try to analyse your graph to see whether the growth fits an exponential curve or not! And anyway, usually there's at least some description of graphs in the text, and some context if it's relevant (say "the drop occured during the week-end, and we later found out the electricity was down for 6 hours in the whole building, cutting of the algae's lighting." Not that it ever happened to me or anything...).

 

I won't comment on your reference list, since the format of those varies between teachers and countries.

 

Overall the whole paper is easy to read and to understand, and it looks nice!

[Viridian]

Whee, biology student here! (I might know a little to much about algae...).

 

Page 3: you wrote "micro algae who", this should be which.

Page 5: "The prepared liquid exists of water and nutrition". I think you have the wrong verb here, I don't understand the sentence.

"a program called imagefocus": Capital I

"After the counting process there will be determined if there can be spoken about exponential growth.". The sentence doesn't work. Try something like: After the counting process (it will be determined / we will determine) if the growth is (indeed/truly/...) exponential.

 

I agree that you need to indicate the units in you result tables. For example, is it just a number of cells, or a concentration in cells/liter? That should be obvious just from reading the table. Adding the note "(cells)" won't look ridiculous, I promise!

 

Also, this could be due to different habits/expectations in your country, but I would expect to see a conclusion/interpretation part after the results. As a clueless reader, I shouldn't have to try to analyse your graph to see whether the growth fits an exponential curve or not! And anyway, usually there's at least some description of graphs in the text, and some context if it's relevant (say "the drop occured during the week-end, and we later found out the electricity was down for 6 hours in the whole building, cutting of the algae's lighting." Not that it ever happened to me or anything...).

 

I won't comment on your reference list, since the format of those varies between teachers and countries.

 

Overall the whole paper is easy to read and to understand, and it looks nice!

Thank you very much for the grammar suggestions. Upon rereading that sentence (after counting the....) it looked really Dutch, my bad. I've added the note (cells) to the table now to clear things up.

 

Also, I did not yet finish the conclusion, discussion or mathematical part when this was uploaded. I've uploaded a new version now.

[livvy]

... You're brilliant. I should've had TDN proofread my research paper. *makes mental note*

 

Mkay, quick grammar note, on page 3, "Algae grow exponential" should be "Algae grow exponentially". Same with "'A' grows exponential" on page 4

 

Um... aside from those few grammatical errors, I don't see many glaring mistakes. I could be super nitpick-y, but unless your paper is going to be judged by a panel of scientists, I see no need to do so. ;)

[Viridian]

Thank you Livvy! Fixed that for the actual paper :) My paper will be judged by my mathematics teacher and my biology teacher, which are both in their 50s and quite knowledgeable.

[livvy]

(say "the drop occured during the week-end, and we later found out the electricity was down for 6 hours in the whole building, cutting of the algae's lighting." Not that it ever happened to me or anything...).

Or "the storage room in which my experiment was done doesn't have heating over the weekend and the cold killed the sea urchin larvae algae." Nothing from personal experience of course. :whistle:

 

If you are being (sort of) judged, there are a few things you may wish to change.

Page 9: "We can find the actual exponential growth by removing the slowing down factors"

It's not technically a slowing factor, it's more of an abnormal data point. A factor would be some sort of change in input (which probably DID happen and resulted in the sudden drop in growth, but the drop itself isn't the factor).

Page 7: "Having added both sequences to the graphical calculator, we’re going to tell him to create a function out of our numbers."

Him? =3 That's adorable. But assuming you actually HAVEN'T named your calculator, you probably mean "it".

Page 8: "If we take of the first 4 numbers, we might get a different result."

o_0 Well, yes, you probably would. But from a science standpoint, why is it okay to remove those points of data? To do something as drastic as cutting four data points, you need some sort of rationale. (Pardon me if I just missed it.)

[Viridian]

Or "the storage room in which my experiment was done doesn't have heating over the weekend and the cold killed the sea urchin larvae algae." Nothing from personal experience of course. :whistle:

 

If you are being (sort of) judged, there are a few things you may wish to change.

Page 9: "We can find the actual exponential growth by removing the slowing down factors"

It's not technically a slowing factor, it's more of an abnormal data point. A factor would be some sort of change in input (which probably DID happen and resulted in the sudden drop in growth, but the drop itself isn't the factor).

Page 7: "Having added both sequences to the graphical calculator, we’re going to tell him to create a function out of our numbers."

Him? =3 That's adorable. But assuming you actually HAVEN'T named your calculator, you probably mean "it".

Page 8: "If we take of the first 4 numbers, we might get a different result."

o_0 Well, yes, you probably would. But from a science standpoint, why is it okay to remove those points of data? To do something as drastic as cutting four data points, you need some sort of rationale. (Pardon me if I just missed it.)

Yes, my calculator's name is Freddie :D Ok, I'll change that :P

 

I removed those numbers to create the actual line that should have been there. I don't know why it took them so long to start growing, as the experiment itself said it should only have taken 2 days. I'll edit it some more and see if I can make it look like I did something useful there, though :P

[The Score in Blue]

May I ask, what year or level is this paper/assignment for?

[Masaryk]

I went through your write-up, and I did quite a bit of editing. Some of the grammar wasn't very clear, and they were all fairly common mistakes, usually with punctuation. As a biologist, myself, your experiment seemed fine, but I did suggest a few language changes.

 

Since this is a high school-level assignment, I wouldn't worry about this too much, but it seemed awkward to me that you used pronouns, like you and we, when describing the methods used. It's probably fine to leave it that way, but for a university-level assignment, I would remove the pronouns.

 

I copied the text into the spoiler below, with the changes and suggestions in red.

 

 

Assignment

 

A bottle with 1l of water, a balanced amount of nutrition, and several algae which are placed between several lamps. Within several days the bottle is full of a green substance. How many algae are in the jar? How did the growth elapse? Can we speak of exponential growth?

 

With a microscope, we can test the process at random moments of the day. To find out, you can take pictures of microscopic views and count the individual cells, with the help of a program, [insert program name], the number of algae. Next you can try to figure out if you can put this data into a mathematical formula.

 

Main question

 

Is the growth of algae exponential?

 

Side Questions

 

What are algae?

How do algae reproduce?

What is exponential growth?

 

Hypotheses:

Algae grow exponentially, so long the circumstances are optimal.

 

Theory:

 

What are algae?

 

Algae are one- and multiple-celled creatures living in water.¹ There are macro and micro algae which vary from seaweed to one-celled creatures. Most are autotrophic and feed themselves. There are only a few algae species which are heterotrophic. Algae are the base of our food chain and are of huge importance [to what?]. About 50% of our oxygen on earth comes from algae.²

 

How do algae reproduce?

 

The algae we work with are one-celled organisms and reproduce by splitting themselves in two.

 

What is exponential growth?

 

An amount called ‘A’ grows exponentially if ‘A’ becomes a certain factor bigger [larger would be a better word to use, grammatically] per time unit.

 

In this formula, ‘A’ is the [final] number of algae and ‘B’ is the start amount, while ‘t’ represents the time and ‘g’ is the increasing factor, which we can derive from our results. With help of a Graphical Calculator (TI 83 +) we will determine the formula for algae growth.

 

Plan of Measurement

Items needed

Several [what material are they made from?]bottles (2)

Clean tubes

Little tap

Fluid for optimal algae conditions (see attachment 1)

Algae

Plastic pipettes

A Bürker-Türk microscopic slide

A Microscope

CMEX-1300x Digital USB-2 camera

The program Imagefocus

Graphic calculator (TI 83 plus)

 

How?

 

The algae will be added to the prepared bottle and will be put near a light source. There is a tube in the bottle which adds air into it and keeps the liquid moving. The prepared liquid consists of water and nutrition (see attachment 1). The addition of air can be regulated by the little tap attached to the tubes.

 

On the start and end of every school day, you will do a measurement, by taking out a small amount of algae and putting them on the Bürker-Türk microscopic slide. With the camera of CMEX you can take pictures of said algae and save them for later.

 

The results will eventually be counted by a program called Imagefocus, which is the software that works with the CMEX camera. After the counting process, we will determine if the growth is exponential. This will be checked with the help of a graphical calculator.

 

Results

 

[insert table here]

* The results of test 10, 11 and 12 are approximate, due to dilution by 10 times.

 

 

Calculations

The result shows us that it the algae were growing exponentially, before it [the experiment?] was cut off for some reason [Do you know the reason? If so, you should state it]. We're going to transform our results into a formula with help of the TI-83 plus. First of all, we have to enter our values into 2 lists.

 

We do this by entering the time values in list 1

 

{6.5,23.5,28.8,47.5, 54.5,71.5,75.5,95.5,100.8,119.5,126.5,143.5} STO [enter]

 

After entering it in list 1, we enter the values of the algae cells in jar 1 in the same way.

 

{0.5, 0.5,0.5,1,1,1.5,5.5,24,63,200,260,300} STO[enter]

 

Having added both sequences to the graphical calculator, we’re going to tell him to create a function out of our numbers.

 

STAT  CALC 0. ExpReg [enter]

 

The two lists above will give us the following information:

 

Y=a*b^x

a=0.1012061697

b=1.059208845

 

Now we are going to check if the data matches up.

STAT PLOTPlot 1On, type (1st), Xlist:L1,Ylist:L2,Mark: (1st)GRAPH

 

This will give us a graph with several dots, showing us how the algae cells have numbered but also how they stopped growing eventually. Now let's see if our formula matches up with the graph shown.

 

Y= VARS5. StatisticsEQRegEQGRAPH

 

The graph we just created does not run the way our dots do, due to the fact that our algae stopped growing exponentially at a certain point. From the way it looks here, they stopped growing exponentially when the last number got added. We will now try to remove this last number of algae cells and remove the last number for time and see what we end up with. We will repeat the whole step.

 

{6.5,23.5,28.8,47.5, 54.5,71.5,75.5,95.5,100.8,119.5,126.5} STO [enter]

{0.5, 0.5,0.5,1,1,1.5,5.5,24,63,200,260} STO[enter]

Y=a*b^x

a=0.09202783

b=1.060675483

 

Both the graphs with and without the last numbers are practically the same, which means that the exponential growth is decided by the first set of numbers, rather than only the last numbers. Since the low numbers climb up so slowly, the exponential graph will be slower as well.

 

If we take of the first 4 numbers, we might get a different result.

 

{54.5,71.5,75.5,95.5,100.8,119.5,126.5,143.5} STO [enter]

{1,1.5,5.5,24,63,200,260,300} STO[enter]

 

Our new numbers are:

a=0.0183100724

b=1.076446355

 

The new graph is a lot closer to our exponential growth and how it would have been if the growth of the algae wouldn't have been slowed down. We can find the actual exponential growth by removing the slowing down factors, which is once again the last number in the rows. We'll repeat all steps with the following numbers:

 

{54.5,71.5,75.5,95.5,100.8,119.5,126.5} STO [enter]

{1,1.5,5.5,24,63,200,260} STO[enter]

 

 

a=0.0076733033

b=1.088137954

 

Because of these new numbers, we can conclude that algae cells indeed grow at an exponential rate. The mathematical formula would be:

 

With N being the number of algae cells and t the time passed in hours.

 

Discussion

 

1.As a European, I should have used commas instead of dots to show decimals. However since we use an American calculator, I used dots for my own convenience.

 

2. I did not use the 2nd jar's information to check if the algae grow exponentially. As you can see in both the graph and the table on page 6, something happened with these algae which somehow forced them to stop growing much earlier than those in the 1st jar, and will therefore give distorted results. The fact that they stopped growing might have had several causes, for example, the fact [is this definitely the cause? If not, you should change 'fact' to 'possibility'] that the bottle was slightly polluted with unknown content which probably came from a dirty pipette. While I am certain I cleaned everything thoroughly before I started the assignment, there something has gone wrong with that bottle. I might also have mixed up liquids when preparing the nutrition, though this is unlikely.

 

3.Algae cells can obviously not grow at an exponential rate forever; this is because they have a lack of living space. In my case this was a 1 liter bottle which was filled all the way with green algae by the end of the assignment. If they had an unlimited living space and unlimited supply of nutrition, they would might have continued to grow at an exponential rate.

 

 

Good luck with your assignment!

[Viridian]

Thank you Masaryk!

 

Yes, it is a highschool level assignment, I guess I'd be in the american year '11' but it count for 10% of my total exam score on my finals for graduating in year 12.... So I'm pretty serious about it :P

 

I've made some final changes, based upon your views here, and hope I'll be in for a good mark :) Hopefully I understood the assignment better than last year.. o.o

 

Time to hand it in! :)